Donkey sentence: Difference between revisions

3 bytes removed ,  15:06, 14 September 2021
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(Created page with "A '''donkey sentence''' is a kind of sentence that occurs in natural language, where an anaphoric pronoun (like {{t|hó}}) refers to a quantified variable (like {{t|sa ảqsh...")
 
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The English sentence is clearly valid English. But the straightforward translation into logic of such a sentence is not well-formed:
The English sentence is clearly valid English. But the straightforward translation into logic of such a sentence is not well-formed:


<blockquote>⚠️ ∀''f'' : (Farmer(''f'') ∧ ∃''d'' [Donkey(''d'') ∧ Owns(''f'', ''d'')]) → Cares(''f'', <u>''d''</u>)].</blockquote>
<blockquote>⚠️ ∀''f'' : Farmer(''f'') ∧ ∃''d'' [Donkey(''d'') ∧ Owns(''f'', ''d'')] → Cares(''f'', <u>''d''</u>).</blockquote>


The underlined instance of variable ''d'' is illegal, because it is outside of the scope of the quantifier ∃''d''.
The underlined instance of variable ''d'' is illegal, because it is outside of the scope of the quantifier ∃''d''.